import React, { Component } from 'react'
import PropTypes from 'prop-types'
import {nanoid} from 'nanoid'
import './index.css'

export default class Header extends Component {

  //对接收的props进行限制：类型、必要性
  static propTypes = {
    addTodo:PropTypes.func.isRequired,
  }

  //键盘事件的回调
  handleKeyUp = (event) => {
    //解构赋值获取target, keyCode
    const { target, keyCode } = event
    //判断是否是回车按键
    if (keyCode !== 13) return
    //添加的todo 名字不能为空
    if (target.value.trim() === '') {
      alert('输入的名字不能为空')
      return
    }
    //准备好一个todo对象
    const todoObj = { id: nanoid(), name: target.value, done: false }
    //将todoObj传递给App父组件
    this.props.addTodo(todoObj)
    //清空输入
    target.value = ''
  }
  render() {
    return (
      <div className="todo-header">
        <input onKeyUp={this.handleKeyUp} type="text" placeholder="请输入你的任务名称，按回车键确认" />
      </div>
    )
  }
}
